The invention concerns a seal (sealing ring) for track chain links on tracked vehicles, in which four chain sprockets, arranged in pairs side-by-side and overlapping in pairs, as well as chain socket, solidly joining the chain members lying axially outside in the overlapping zone and a coaxial bolt solidly joining the chain members lying axially inside in the overlapping zone, form a chain link which can be lubricated from a bore in the bolt which can be filled with lubricant, through a radial bore in the bolt, each sprocket lying outside, in the overlapping zone, having on its inner side a round cylindrical depression to receive the seal and a rigid distancing ring, sitting on the end of the bolt extending out of the socket, while the bottom surface of the depression, lying in one radial plane, lies opposite the end surface of the sprocket next to the depression, lying in a parallel plane, and the overlapping sprockets form a ring gap which opens the hollow space limited by the depression and the end surface lying axially opposite same; the seal, consisting of a softer solid ring, sealing statically against a boundary surface of the depression, and of a harder, more wear-resistant flange ring, which lies against the ring-form, coaxial boundary surface of the depression and seals dynamically against the end surface axially opposite the depression, with stress on the link while the flange ring supports the solid ring both axially and radially, and between each of these rings, on the one hand, and the distancing ring, on the other hand, a distance is present.
In the seals (sealing rings) of this kind known from German Pat. No. 2,205,533 and U.S. Pat. No. 3,336,086, the flange ring has a substantially U-shaped profile with substantially parallel legs, which are formed by two ring-form flanges, of which the axially inner has a circumferential sealing edge, which is deformed under axial pressure to a narrow, ring-form sealing surface, and by which the axially inner flange, after the installation of the flange ring, is pressed into the ring-form corner at the bottom of the depression receiving the seal. The profile yoke, joining the profile legs of the flange ring is formed by a narrow or broader radial inner ring, as the case may be, against which the flanges are formed and which is arranged between the solid ring, on the one hand, and the rigid distancing ring, on the other, which forms a loose individual part or a component part formed on the chain member lying axially inside in the zone of overlapping. The solid ring is situated between the two flanges of the flange ring, of which the ring groove formed by the flanges is completely or partly filled, and is therefore pressed by the flange ring against the ring-form coaxial boundary surface of the depression.
With the two known seals, the problem to be solved is to prevent, at the same time, the exit of lubricant through the ring gap in one direction, and the entrance of dirt through the ring gap in the other direction. But even with a linked connection of the two flanges of the flange ring and with a complete filling of the ring groove of the flange ring by means of the solid ring, it is a disadvantage that the dynamic sealing edge on the axial outer flange of the flange ring gives only a narrow sealing surface which is too small to be able to prevent satisfactorily the exit of lubricant and the entrance of dirt. Actually, it has been shown in seals of the kind mentioned, tested in practice, that grains, of sand, for example, which have migrated into the plastic material of the flange ring in the zone of the sealing surface, have become imbedded in this sealing surface and have damaged the adjacent part of the metal end surface lying opposite. It is also a disadvantage in the two known seals, that the size and shape of the cross-section area of the rubber elastic solid ring under load, and its arrangement, do not suffice to give the seal that axial elasticity which it needs in order to compensate tolerances in the production of the chain sprockets, to be sufficient for axial stresses in all cases, and to assure, through a flat spring curve, as constant as possible a pressure in the contact between the narrow sealing surface of the flange ring and the neighboring end surface of a chain sprocket.
The invention attacks, therefore, the problem of providing a seal for track chain links on tracked vehicles, without the said disadvantages which eliminates with certainty the said problem of substance exchange and improves the springing distance of the seal.